It is generally believed that antimicrobial peptide has a broad antimicrobial spectrum such that drug resistant bacterium hardly appears, and therefore antimicrobial peptide is expected to be used for the purpose of preventing and treating bacterial infectious diseases in human beings and animals or providing antimicrobial properties to products such as food. A large number of antimicrobial peptides have been isolated from various animals and plants to date.
For example, a variety of antimicrobial peptides are disclosed in Japanese Laid-Open Patent Publication No. 2000-63400, Japanese Laid-Open Patent Publication No. 2001-186887, International Publication No. WO98/51794, International Publication No. WO99/26971, International Publication No. WO00/09553, International Publication No. WO00/59527 and International Publication No. WO01/09175. In addition, artificially synthesized antimicrobial peptides, which are designed and created by utilizing known amino acid sequence of which relations with antimicrobial properties have never been discussed, are reported in International Publication No. WO03/91429.